This invention relates to motor vehicle friction clutches and, particularly, to devices which operate friction clutches automatically by means of a controllable drive that moves an actuator between engaged and disengaged positions.
Automatic motor vehicle gear shifts customarily employ torque converters which require large investment in equipment and, hence, are relatively expensive. To reduce structural expenditures, attempts have been made to operate conventional motor vehicle friction clutches with centrifugal force switches that engage the clutch above idling speeds. Such clutches have proven to offer only limited capability because the rotating speed/dependent engagement characteristic of the centrifugal force switch adjusts to the rotary speed torque characteristic of the motor only with great difficulty. To make starting on a hill possible, the engagement point of the centrifugal switch must be set in the region of maximum torque, and, thus, at a relatively high engine speed. Consequently, a system using such a device must start at relatively high engine speeds even on level ground. This is bothersome, particularly when maneuvering the vehicle back and forth.
An object of the invention is to improve automatic motor vehicle friction clutches and the controls therefor.
Another object of the invention is to avoid the aforementioned difficulties.
Still another object of the invention is to adapt the engagement behavior of a conventional automatic motor vehicle friction clutch to a wide gamut of driving situations.
Yet another object of the invention is to achieve the above in an uncomplicated manner.